If the bending torque of a carton's folding line (depressed line) is abnormal, then when the carton is loaded on a box manufacturing machine, a boxing machine or the like it may be unsatisfactorily opened or folded, or may be cracked. Accordingly, in order to eliminate such difficulties, it is necessary to measure the bending torque in advance, thereby to determine whether or not the bending characteristic is acceptable. However, the measurement of the bending torque takes a considerably long period of time. Therefore, a simple method has been employed in which the height of a depressed line which is in correlation with the bending torque is measured with a dial gauge or the like. More specifically, a specimen is inserted between the surface table and the measuring element, a zero reference is determined from a flat part of the specimen where no depressed line is formed, and thereafter the height of a depressed line is measured. And, in order to measure the height of the next depressed line, it is necessary to determine the zero reference again.
As is apparent from the above description, the method is disadvantageous in that as it is necessary to determine the zero reference for every depressed line, it still takes much time.
In view of the foregoing, this utility model is intended to provide a device which can automatically convey a specimen and automatically carry out the determination of a zero reference for every depressed line, the measurement of a depressed line height and the displaying and recording of the value of the height thus measured.